The invention herein relates generally to an expandable shaft, to be utilized primarily on slitter or rewinder machines in the paper and plastics industries, which is particularly adapted to mount and stabilize support tubes or cores, mandrels, blade holders, working tools, and the like.
Expandable shafts are well-known in the art as exemplified by the following U.S. Pat. Nos.
2,849,192 -- Fairchild
3,053,467 -- Gidge
3,173,325 -- Warren et al
3,742,714 -- Thomas
The patents to Fairchild and Gidge illustrate rigid perforated metal shafts with internal elastomeric liners which, upon the introduction of internal pressure, expand through and beyond the perforation with knob-like protrusions which individually grip the member within which the shaft is received.
Warren et al and Thomas disclose hollow steel shafts which expand upon the introduction of internal pressure for a smooth surface engagement with working tools received thereover.
Neither of the above two systems has been found entirely satisfactory in that, while the solid expandable steel shafts provide a straight and true surface, the metal-to-metal contact gives rise to the possibility of relative rotation, slippage or traveling between the shaft and the work piece thereon. By the same token, the use of projecting elastomeric gripping knobs raises problems with regard to alignment and stability, particularly when working with relatively short work pieces, such as blade holders and the like.